1. Field of the Invention
The present invention relates to an exhaust system of an engine.
2. Description of Background Art
An exhaust system of an engine includes an inner pipe provided with a plurality of vent holes connected to an exhaust pipe at an upstream end portion, an outer pipe configured to surround the inner pipe by forming an annular chamber between the inner pipe and the outer pipe and glass wool that is a noise absorbing material filled in the annular chamber, to reduce exhaust noise has been known in the related art. See, for example, JP-A No. 2010-216340.
The exhaust system of the engine described in JP-A No. 2010-216340 is able to reduce exhaust noise, but fails to improve the output of the engine.